POS1220 TRANSITION IN SYMPTOMS, ORGAN INVOLVEMENT, AND CLINICAL DIAGNOSIS OF PATIENTS POSITIVE FOR ANTI-ARS ANTIBODIES
Authors: S. Inotani, Y. Kondo, S. Takanashi, S. Ishigaki, S. Saito, M. Takeshita, J. Kikuchi, H. Hanaoka, K. Suzuki, Y. Kaneko
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Myositis-specific autoantibodies are useful biomarkers to make a diagnosis and predict prognosis of idiopathic inflammatory myopathies. Anti-aminoacyl transfer RNA synthetase antibodies (anti-ARS) is one of the most representative myositis-specific autoantibodies, however, organ involvement in patients positive for anti-ARS is not limited to the muscles but also skin, joints, and lungs, which constructs spectrums of idiopathic inflammatory myopathies called anti-synthetase syndrome. While individual anti-ARS antibodies have been known to form distinct clinical subsets, little is known regarding their chronological clinical presentation patterns and diagnosis during clinical course. <h3>Objectives</h3> To clarify the clinical characteristics of patients positive for anti-ARS and transition in manifestations and diagnosis during their clinical courses. <h3>Methods</h3> We reviewed consecutive patients with anti-ARS who had visited our hospital between 1998 and 2022 retrospectively. Anti-ARS antibodies were detected and categorized with RNA immunoprecipitation assays. We collected patient clinical characteristics and laboratory parameters including transition of diagnosis, manifestations and, organ involvement from their medical records chronologically. All statistical analyses were performed using JMP 15 (SAS Institute Inc., Cary, NC, USA). <h3>Results</h3> We included 97 patients positive for anti-ARS in the analysis. The mean age was 53.2 years old, and 73 (75%) were female. The types of anti-ARS Ab were anti-Jo-1 (37%), anti-EJ (32%), anti-PL-7 (11%), anti-PL-12 (12%), anti-KS (4%), and anti-OJ (3%). Half of the patients had co-existing other autoantibodies such as anti-SS-A/Ro, anti-SS-B/La, anti-dsDNA, anti-RNP, and/or rheumatoid factor, but the combination of antibodies was not different among each anti-ARS. The initial diagnoses of the patients were polymyositis (22%), dermatomyositis (33%), amyopathic dermatomyositis (13%), and interstitial pneumonia with autoimmune features (27%). Raynaud's phenomenon were observed in 25% of the patients; 19% in patients with anti-Jo-1, 36% in anti-EJ, 11% in anti-PL-7, 30% in anti-PL-12, 25% in anti-KS, and 33% in anti-OJ antibodies. Interstitial lung disease was observed in all patients except for three (two with anti-Jo-1 and one with anti-PL-12). Myositis was diagnosed initially in 72% of patients with anti-Jo-1, 50% with anti-EJ, 40% with anti-PL-7, 42% with anti-PL-12, none with anti-KS, and 67% with anti-OJ antibodies, but additional 6%, 4%, 40%, 8%, 0%, and 0% with those individual antibodies, respectively, were diagnosed with myositis during the mean observation period of 9.6 years. Acute or subacute exacerbation of interstitial lung disease requiring immunosuppressive treatment intensification were observed in 28% of patients with anti-Jo-1, 33% with anti-EJ, 40% with anti-PL-7, 8% with anti-PL-12, 33% with anti-KS, and 67% with anti-OJ antibodies. <h3>Conclusion</h3> Almost all patients positive for anti-ARS positive had interstitial lung disease irrelevant of myositis diagnosis. Patients with anti-Jo-1 were suffering from typical myositis complicated with interstitial lung diseases at initial diagnosis, while patients with anti PL-7 tended to have precedent interstitial lung disease followed by development of myositis during clinical courses. The incidence of acute exacerbation of interstitial lung disease was the lowest in patients with anti-PL12. <h3>REFERENCES:</h3> NIL. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.